/* Id */

/*
 * Copyright (c) 1988-1997 Sam Leffler
 * Copyright (c) 1991-1997 Silicon Graphics, Inc.
 *
 * Permission to use, copy, modify, distribute, and sell this software and 
 * its documentation for any purpose is hereby granted without fee, provided
 * that (i) the above copyright notices and this permission notice appear in
 * all copies of the software and related documentation, and (ii) the names of
 * Sam Leffler and Silicon Graphics may not be used in any advertising or
 * publicity relating to the software without the specific, prior written
 * permission of Sam Leffler and Silicon Graphics.
 * 
 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND, 
 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY 
 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.  
 * 
 * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
 * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
 * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
 * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF 
 * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE 
 * OF THIS SOFTWARE.
 */

#include "tiffiop.h"
#ifdef NEXT_SUPPORT
/*
 * TIFF Library.
 *
 * NeXT 2-bit Grey Scale Compression Algorithm Support
 */

#define SETPIXEL(op, v) {                       \
        switch (npixels++ & 3) {                \
        case 0: op[0]  = (unsigned char) ((v) << 6); break;     \
        case 1: op[0] |= (v) << 4; break;       \
        case 2: op[0] |= (v) << 2; break;       \
        case 3: *op++ |= (v);      break;       \
        }                                       \
}

#define LITERALROW      0x00
#define LITERALSPAN     0x40
#define WHITE           ((1<<2)-1)

static int
NeXTDecode(TIFF* tif, tidata_t buf, tsize_t occ, tsample_t s)
{
        register unsigned char *bp, *op;
        register tsize_t cc;
        register int n;
        tidata_t row;
        tsize_t scanline;

        (void) s;
        /*
         * Each scanline is assumed to start off as all
         * white (we assume a PhotometricInterpretation
         * of ``min-is-black'').
         */
        for (op = buf, cc = occ; cc-- > 0;)
                *op++ = 0xff;

        bp = (unsigned char *)tif->tif_rawcp;
        cc = tif->tif_rawcc;
        scanline = tif->tif_scanlinesize;
        for (row = buf; (long)occ > 0; occ -= scanline, row += scanline) {
                n = *bp++, cc--;
                switch (n) {
                case LITERALROW:
                        /*
                         * The entire scanline is given as literal values.
                         */
                        if (cc < scanline)
                                goto bad;
                        _TIFFmemcpy(row, bp, scanline);
                        bp += scanline;
                        cc -= scanline;
                        break;
                case LITERALSPAN: {
                        int off;
                        /*
                         * The scanline has a literal span
                         * that begins at some offset.
                         */
                        off = (bp[0] * 256) + bp[1];
                        n = (bp[2] * 256) + bp[3];
                        if (cc < 4+n || off+n > scanline)
                                goto bad;
                        _TIFFmemcpy(row+off, bp+4, n);
                        bp += 4+n;
                        cc -= 4+n;
                        break;
                }
                default: {
                        register int npixels = 0, grey;
                        unsigned long imagewidth = tif->tif_dir.td_imagewidth;

                        /*
                         * The scanline is composed of a sequence
                         * of constant color ``runs''.  We shift
                         * into ``run mode'' and interpret bytes
                         * as codes of the form <color><npixels>
                         * until we've filled the scanline.
                         */
                        op = row;
                        for (;;) {
                                grey = (n>>6) & 0x3;
                                n &= 0x3f;
                                while (n-- > 0)
                                        SETPIXEL(op, grey);
                                if (npixels >= (int) imagewidth)
                                        break;
                                if (cc == 0)
                                        goto bad;
                                n = *bp++, cc--;
                        }
                        break;
                }
                }
        }
        tif->tif_rawcp = (tidata_t) bp;
        tif->tif_rawcc = cc;
        return (1);
bad:
        TIFFErrorExt(tif->tif_clientdata, tif->tif_name, "NeXTDecode: Not enough data for scanline %ld",
            (long) tif->tif_row);
        return (0);
}

int
TIFFInitNeXT(TIFF* tif, int scheme)
{
        (void) scheme;
        tif->tif_decoderow = NeXTDecode;
        tif->tif_decodestrip = NeXTDecode;
        tif->tif_decodetile = NeXTDecode;
        return (1);
}
#endif /* NEXT_SUPPORT */

/* vim: set ts=8 sts=8 sw=8 noet: */
